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GEOLOGY OF THE INTERMOUNTAIN WEST
an open-access journal of the Utah Geological Association
Volume 3 2016
TRACKING DINOSAURS IN BLM CANYON COUNTRY, UTAH
ReBecca K. Hunt-Foster, Martin G. Lockley, Andrew R.C. Milner, John R. Foster, Neffra A.
Matthews, Brent H. Breithaupt, and Joshua A. Smith
A Field Guide Prepared For
SOCIETY OF VERTEBRATE PALEONTOLOGY
Annual Meeting, October 26 – 29, 2016
Grand America Hotel
Salt Lake City, Utah, USA
© 2016 Utah Geological Association. All rights reserved.
For permission to copy and distribute, see the following page or visit the UGA website at www.utahgeology.org for information.
Email inquiries to GIW@utahgeology.org.
GEOLOGY OF THE INTERMOUNTAIN WEST
an open-access journal of the Utah Geological Association
Volume 3 2016
Editors UGA Board
Douglas A. Sprinkel Thomas C. Chidsey, Jr. 2016 President Bill Loughlin bill@loughlinwater.com 435.649.4005
Utah Geological Survey Utah Geological Survey 2016 President-Elect Paul Inkenbrandt paulinkenbrandt@utah.gov 801.537.3361
801.391.1977 801.537.3364 2016 Program Chair Andrew Rupke andrewrupke@utah.gov 801.537.3366
GIW@utahgeology.org tomchidsey@utah.gov 2016 Treasurer Robert Ressetar rrgeology@gmail.com 801.949.3312
2016 Secretary Tom Nicolaysen tnicolaysen@utah.gov 801.538.5360
2016 Past-President Jason Blake blake-j@comcast.net 435.658.3423
Bart J. Kowallis Steven Schamel
Brigham Young University GeoX Consulting, Inc.
801.422.2467 801.583-1146 UGA Committees
bkowallis@gmail.com geox-slc@comcast.net Education/Scholarship Loren Morton lmorton@utah.gov 801.536.4262
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Society of Vertebrate Paleontology AAPG House of Delegates
2016-2018 Term Craig Morgan craigmorgan@utah.gov 801.422.3761
Editors
James I. Kirkland (Editor-in-Chief) — Utah Geological Survey State Mapping Advisory Committe
ReBecca Hunt-Foster — Bureau of Land Management
UGA Representative Jason Blake blake-j@comcast.net 435.658.3423
Greg McDonald — Bureau of Land Management
Martha Hayden — Utah Geological Survey
Earthquake Safety Committe
Production Chair Grant Willis gwillis@utah.gov 801.537.3355
Cover Design and Desktop Publishing UGA Website
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www.utahgeology.org
Cover Webmasters Paul Inkenbrandt paulinkenbrandt@utah.gov 801.537.3361
A Navajo Sandstone scene from 185 million years ago. Lance Weaver lanceweaver@utah.gov 801.403.1636
A variety of vertebrates stroll and swim near an inter-
dunal lake “oasis” while small animals take refuge in
UGA Newsletter
Newsletter Editor Bob Biek bobbiek@utah.gov 801.537.3356
their burrows and pterosaurs fly overhead. Artwork by
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i
GEOLOGY OF THE INTERMOUNTAIN WEST
an open-access journal of the Utah Geological Association
Volume 3 2016
Tracking Dinosaurs in BLM Canyon Country, Utah
ReBecca K. Hunt-Foster1, Martin G. Lockley2, Andrew R.C. Milner3, John R. Foster4, Neffra A. Matthews5,
Brent H. Breithaupt6, and Joshua A. Smith7
1
Bureau of Land Management – Canyon Country District, 82 East Dogwood, Moab, Utah 84532; rhuntfoster@blm.gov
2
University of Colorado Denver, Campus Box 172, University of Colorado Denver, PO Box 173364, Denver, Colorado 80217; martin.lockley@
ucdenver.edu
3
St. George Dinosaur Discovery Site at Johnson Farm, 2180 East Riverside Drive, St. George, Utah 84790; arcmilner@gmail.com
4
Museum of Moab, 118 East Center Street, Moab, Utah 84532; director@moabmuseum.org
5
Bureau of Land Management National Operations Center, Geospatial Section, Denver Federal Center, Bldg. 50, P.O. Box 25047, OC-534,
Denver, Colorado 80225-0047; n1matthe@blm.gov
6
Bureau of Land Management, 5353 Yellowstone Road, Cheyenne, Wyoming 82009; bbreitha@blm.gov
7
Dominguez Anthropological Research Group (DARG), P.O. Box 3543, Grand Junction, Colorado 81502; dinotrack@hotmail.com
ABSTRACT
The remarkably extensive and abundant Mesozoic-aged exposures on public lands around Moab have
made this region well known for ichnofossils. The nearly complete record of Upper Triassic through Low-
er Cretaceous rocks exposed in this area is well known for its sheer abundance of tracks and traces. This
three-day field trip will visit many important classic and new sites exposed in the Bureau of Land Manage-
ment’s Canyon Country District. This field trip guidebook will give one an overview of the major sites we
will visit, as well as a brief summary of work previously done in these areas.
FIELD TRIP OVERVIEW of a turning sauropod in the Upper Jurassic Morrison
Formation, along with the first Hispanosauropus tracks
On Day 1, the field trip will start in Salt Lake City
identified outside Europe (Foster, 2015). This trackway
and travel south on Interstate 15 (I-15) exiting at Spanish
has historically been attributed to a limping theropod.
Fork, where we will proceed on U.S. Highway 6 across
Soldier Summit through Price to Green River between Immediately following we will visit the Mill Canyon
the San Rafael Swell to the west and the Book Cliffs (fig- Dinosaur Tracksite (Cedar Mountain Formation; Ruby
ure 1). We will continue east on Interstate 70 (I-70) con- Ranch Member). This newly discovered tracksite pre-
tinuing along the south side of the Book Cliffs. This tran- serves one of the most diverse and largest Early Creta-
sect represents one of the longest continuous exposures ceous dinosaur tracksites in North America and was the
of the regressing Late Cretaceous coastline anywhere in subject of recent interpretive efforts by the Bureau of
North America (Van Wagoner and others,1991; Kirk- Land Management (BLM). If time allows, we will visit
land and others, 2016). Our first stop will be the Copper a possible cynodont burrow complex found in the erg
Ridge Dinosaur Tracksite, where we will view the tracks deposits of the Lower Jurassic Navajo Sandstone west of
Citation for this article.
Hunt-Foster, R.K., Lockley, M.G., Milner, A.R.C., Foster, J.R., Matthews, N.A., Breithaupt, B.H., and Smith, J.A., 2016, Tracking dinosaurs
in BLM canyon country, Utah: Geology of the Intermountain West, v. 3, p. 67–100.
© 2016 Utah Geological Association. All rights reserved.
For permission to use, copy, or distribute see the preceeding page or the UGA website, www.utahgeology.org, for information. Email inquiries to GIW@utahgeology.org.
67
Tracking Dinosaurs in BLM Canyon Country, Utah
Hunt-Foster, R.K., Lockley, M.G., Milner, A.R.C., Foster, J.R., Matthews, N.A., Breithaupt, B.H., and Smith, J.A.
Figure 1. (A) Field trip route. (B) Day one stops: 1 – Copper Ridge Dinosaur Tracksite, 2 – Mill Canyon Dinosaur Tracks,
and 3 – Synapsid Burrows. (C) Day two stops: 4 and 5 – Lisbon Valley and the Last Phytosaur, 6 – Shay Canyon, 7 – Track
City, and 8 – Bridger Jack Mesa. (D) Day three stops: 9 – Bull Canyon Dinosaur Tracks, 10 – Poison Spider Dinosaur Tracks,
11 – Moline Reef Tracksite, and 12 – Utah State University–Eastern Prehistoric Museum.
Geology of the Intermountain West 68 2016 Volume 3
Tracking Dinosaurs in BLM Canyon Country, Utah
Hunt-Foster, R.K., Lockley, M.G., Milner, A.R.C., Foster, J.R., Matthews, N.A., Breithaupt, B.H., and Smith, J.A.
Moab. We will spend the evening in Moab. resentative are those of the famous Chirotherium or
Day 2 will consist of driving south to the Indian “chirothere” (meaning hand animal) group. These have
Creek and Lisbon Valley areas to view tracks in the a global distribution and have been well-documented
Chinle, Wingate, and Navajo Formations, along with in the western United States by Peabody (1948) espe-
the Last Phytosaur—a cast of a phytosaur skull pressed cially in the Moenkopi Formation of northern Arizona.
into the basal-most sands of the Triassic-Jurassic Win- Peabody, however, also described swim tracks from
gate Sandstone. We will view a variety of Eubrontes and Utah, which he attributed to amphibians. The Upper
Grallator tracksites, including archosauromorph and Triassic Chinle Formation has proved a rich source of
dicynodont tracks. We will return to Moab for the eve- both tracks and body fossils as described in this guide
ning. and in Martz and others (2014). Chinle Formation
Day 3 we will visit the Fisher Mesa Tracksite on tracks are particularly diverse, and include the ubiqui-
Forest Service land in the La Sal Mountains. This Mid- tous tridactyl theropod track Grallator, which is argu-
dle Jurassic Entrada Sandstone tracksite is part of the ably the first unequivocally identified dinosaur track,
Moab “Megatracksite” that preserves millions of Mega- although the rare track Atreipus may be as old. A zone
losauripus tracks in the Moab area. Afterwards we will with abundant small Grallator tracks, also identified in
visit our last Moab area site, the Poison Spider Tracksite, Europe, has been interpreted as evidence of the early
where we will view Eubrontes, Grallator, and the type of global radiation of small theropods. Associated Chinle
small bird-sized Anomoepus moabensis in an oasis de- tracks, found abundantly in the Moab area, and else-
posit within the Navajo Sandstone. We will then travel where in Utah, include Brachychirotherium, probably
to the new Moab Giants Museum for a tour of the facil- representing an aetosaur, the lacertiform ichnogenus
ities before heading through the San Rafael Swell where Rhynchosauroides, and the less common Apatopus, of
we will visit the Moline Reef Tracksite (also called the probable phytosaur affinity. These assemblages are as-
Moore Tracksite) in the Turonian Ferron Sandstone. sociated with diverse Chinle plant fossils, indicative of
Our last stop will be at the Utah State University Eastern humid paleoenvironmental conditions that generated
Prehistoric Museum in Price, where we will view tracks paleosol and fluvio-lacustrine deposits containing fish-
found in the Upper Cretaceous Mesaverde Group from es, amphibians, phytosaurs, and other aquatic fauna.
the surrounding Book Cliffs before returning to Salt The transition from the Chinle Formation to the
Lake City. Final schedule will be flexible to accommo- Upper Triassic-Lower Jurassic Glen Canyon Group,
date maximum tracking opportunities (figure 1). consisting, in ascending order of the Wingate, Kayenta,
and Navajo Formations, marks a very significant change
INTRODUCTION TO TRACKS OF THE in paleoenvironmental conditions. The Upper Triassic-
Lower Jurassic Wingate and Lower Jurassic Navajo
MOAB AREA
Sandstones predominantly consist of dune sands with
The prehistoric track record in Utah is exceptional- the sandy fluviatile facies of the Lower Jurassic Kayenta
ly good, particularly in southeastern Utah. Fossil foot- in between. All three formations are locally track rich
prints are found abundantly in most terrestrial deposits but almost devoid of body fossils. There is a marked
from the Late Paleozoic through Cenozoic and are di- change in the track assemblages (ichnofaunas) just
verse, well-documented and represented at an extraor- above the base of the Wingate where the aforemen-
dinarily large number of sites (Lockley and Hunt, 1995). tioned Chinle ichnofauna is replaced by a fauna con-
In the Moab area, abundant sites are known from most taining Grallator and Eubrontes (both representing
Mesozoic terrestrial formations. The most representa- theropods), Otozoum (prosauropod track), Anomoepus
tive track assemblages and sites from this area represent (ornithischian), and Batrachopus (small, terrestrial
the main focus of this guide and field trip. crocodylomorph). One small Anomoepus morphotype
Early and Middle Triassic track assemblages are has been named A. moabensis (Lockley and Gierlinski,
dominated by archosaur tracks. Among the most rep- 2006; Lockley and others, 2014a). This is typical of Early
Geology of the Intermountain West 69 2016 Volume 3
Tracking Dinosaurs in BLM Canyon Country, Utah
Hunt-Foster, R.K., Lockley, M.G., Milner, A.R.C., Foster, J.R., Matthews, N.A., Breithaupt, B.H., and Smith, J.A.
Jurassic assemblages worldwide and has been referred (sauropod and theropod) tracksites. A few sites have
to as the first truly global tetrapod track biochron also yielded ornithischian tracks including the type of
(Lucas, 2007). Facies variation is important in these Stegopodus, from near Moab airport (Lockley and Hunt,
formations, with the Moenave Formation in south- 1998). Crocodylian and turtle tracks also occur at a few
west Utah (partly equivalent to the Wingate Sandstone sites, including the type of Hatcherichnus, a crocodylian
in southeastern Utah) representing a fluvio-lacustrine swim track with associated sinuous tail traces (Foster
system in this region, and has yielded theropod swim and Lockley, 1997).
tracks around St. George (Milner and others, 2006c). The Cretaceous track record in southeastern Utah is
Likewise, the Kayenta Formation transitions into a silty represented by Lower Cretaceous assemblages from the
facies in northern Arizona and southwestern Utah. The Cedar Mountain Formation and the Naturita Forma-
synapsid track Brasilichnium, which is difficult to dis- tion (formerly known as the Dakota Formation), with
tinguish from Permian Chelichnus also occurs in the the Upper Cretaceous assemblages from the broadly
dune facies with Octopodichnus and small Grallator defined Mesaverde Group. Recent studies of the Ce-
tracks, especially in the Navajo Sandstone, long regard- dar Mountain have revealed the first dromaeosaurid
ed as a classic dune (erg) deposit. The Navajo contains trackways from North America, and an assemblage of
localized playa deposits with algal carbonates and zones bird tracks (Aquatilavipes) that are arguably the oldest
with fossil wood; all evidence of pluvial periods. evidence of birds from North America (Lockley and
The tetrapod record for the Middle Jurassic is rather others, 2014b, 2015). In contrast to the Cedar Moun-
sparse both in Utah and globally. The Carmel Formation tain Formation, which is rich in bone sites and contains
has produced Carmelopodus, from near Vernal, and skeletal and track evidence of sauropods, the overly-
the dune facies of the Entrada Sandstone has pro- ing Naturita Formation, although very track-rich, is
duced the small terrestrial crocodylian Entradasuchus almost completely devoid of tetrapod body fossils and
and a few small theropod tracks. By contrast the up- contains no track evidence of sauropods, apparently
permost surface of the Entrada around Moab, where it marking the beginning of the so called “sauropod hi-
represents the interface with the marine, upper tongue atus.” Although containing abundant track evidence of
of the Summerville Formation, has produced abun- theropods (Lockley, 2016), ornithopods, ankylosaurs,
dant theropod tracks assigned to the ichnogenera pterosaurs, crocodylians, and turtles, most of the bet-
Megalosauripus and Therangospodus, and two isolated ter-documented Naturita Formation tracksites occur in
occurrences of sauropod tracks of which only one site Colorado. Nevertheless, sites with ornithopods, thero-
has been described by Foster and others (2000) as the pod, and crocodylian tracks have been reported from
oldest recorded in North America. This aggradational Utah. Moreover, given that the Colorado sites represent
flooding surface has produced a regionally extensive a vast dinosaur freeway associated with coastal plain
track zone known as the Moab Megatracksite, which aggradation along the margins of the Western Interior
covers an area of several hundred square km (Lockley, Seaway, the Naturita Formation tracksite occurrences
1997). Megatracksites, also popularly known as dino- in Utah must be considered an integral part of the dino-
saur freeways, can be attributed to the dynamics of saur freeway complex.
sea level change associated with coastal plain systems. The Upper Cretaceous coal-bearing Mesaverde
Immediately above the megatracksite surfaces, in thin Group, the youngest Mesozoic-aged rocks in south-
upper Summerville deposits, abundant pterosaur tracks eastern Utah, are also historically famous for dinosaur
(ichnogenus Pteraichnus) occur in marginal marine tracks, including miscellaneous theropod and giant
deposits along with a few theropod tracks. This unit hadrosaur tracks, some of which were excavated early
marks the transition into the Upper Jurassic, which is in the 20th century. There have also been scattered re-
mainly represented by the Morrison Formation, con- ports of a few sites yielding pterosaur, bird, mammal,
taining abundant tetrapod skeletal remains and a some- and frog tracks. Recent studies indicate as yet undocu-
what more scattered record of saurischian-dominated mented turtle, ceratopsian, and therizinosaur tracks
Geology of the Intermountain West 70 2016 Volume 3
Tracking Dinosaurs in BLM Canyon Country, Utah
Hunt-Foster, R.K., Lockley, M.G., Milner, A.R.C., Foster, J.R., Matthews, N.A., Breithaupt, B.H., and Smith, J.A.
Although tetrapod tracks are abundant and diverse all managed by the BLM – Canyon Country District Of-
in the Mesozoic of southeastern Utah, the question fice, unless otherwise noted. Please remember that it is
arises as to their utility in paleobiology. Clearly they illegal to collect or take vertebrate body fossils, as well
are important indicators of behavior, helping distin- as casts or molds of vertebrate trace fossils, including
guish walkers from runners, sprawling from erect gaits, the use of latex, or other surface disturbing activities,
obligatory from facultative bipeds and quadrupeds, and without a permit under the Paleontological Resources
solitary from gregarious tendencies. We also find evi- Preservation Act of 2009. Any excavations or clearance
dence of swimming among theropods, crocodylians, of the below mentioned sites have been done by permit-
turtles, and pterosaurs (Milner and Lockley, 2016), or ted paleontologists through the BLM, or other appro-
even indications of theropod courtship (Lockley and priate agencies. The BLM maintains six publicly inter-
others, 2016b). It is also accepted that because tracks preted tracksites within the Canyon Country District,
represent in situ evidence of living animals, they have of which we will visit three examples – Copper Ridge,
value for paleoecological census purposes. Formations Poison Spider, and Mill Canyon.
have been categorized on the basis of the relative num-
ber of sites yielding tetrapod tracks versus skeletal re- DAY 1: MIDDLE JURASSIC – EARLY
mains (Lockley, 1991). Regionally, a surprising number
CRETACEOUS OF GRAND COUNTY
of formations yield only tracks (Type 1), or are heavily
track-dominated (Type 2): e.g., Wingate, Navajo, Entra- Stop 1 – Copper Ridge
da, Summerville, and Naturita. In contrast, formations
dominated by skeletal remains and relatively few tracks The Copper Ridge Tracksite (sometimes referred
(Type 4): e.g., Morrison and Cedar Mountain Forma- to as the Valley City site, e.g., Lockley and Hunt, 1995,
tions are less common, and there are no bone-bearing or the Turning Sauropod site, e.g., Barnes, 1997) was
formations which lack tracks entirely (Type 5). Forma- discovered in the 1980s and was reported by Lockley
tions with equal number of vertebrate track and verte- and Hunt (1995), who also published a map of the site
brate body fossil sites are classified as Type 3. This re- (figure 2). The tracksite level is in the upper few meters
inforces the conclusion that tracks are abundant and of the Salt Wash Member of the Morrison Formation,
useful in helping characterize faunas associated with on a current-ripple-marked surface of sandstone likely
given deposits. It is also well known that track assem- representing a sand bar lateral to a fluvial channel. It is
blages are often consistent within given sedimentary fa- Late Jurassic, most likely Kimmeridgian in age.
cies. This gives rise to the ichnofacies concept, the clas- Trackways at the site include a large sauropod (ich-
sic example being the dune or Chelichnus ichnofacies, nogenus Brontopodus, figure 2) making a nearly 90-de-
which gives insight into Permian through Jurassic and gree right turn and a large theropod with an apparent
even some Cenozoic dune-dwelling faunas. The most limp. Several other smaller, isolated tracks of thero-
diverse tetrapod ichnofaunas appear to occur in flu- pods are preserved around the sauropod trackway. The
vio-lacustrine and floodplain paleoenvironments such large, possibly limping theropod trackway has recent-
as are represented by various Chinle, Morrison, and ly been assigned to the ichnogenus Hispanosauropus
Cedar Mountain deposits. The Naturita Formation and (Foster, 2015, figure 2). Hispanosauropus, previously
Mesaverde Group also yield diverse ichnofaunas associ- known from the Upper Jurassic of Europe, is distinct
ated with what can be broadly defined as well-vegetat- from Megalosauripus and most likely was made by
ed, coal-producing coastal plain systems, which in turn an allosauroid theropod, although it might have been
generate regionally extensive megatracksite or dinosaur made by a spinosauroid (torvosaurid) or a ceratosau-
freeway complexes shaped by sea level dynamics. roid. Close geographic and stratigraphic association of
This field trip guide will take one through each site Hispanosauropus with the large theropod body fossil
we will visit during the 2016 Society of Vertebrate Pa- taxa Allosaurus, Torvosaurus, and Ceratosaurus in both
leontology Field Trip of the same name. These sites are North America and the Iberian Peninsula strength-
Geology of the Intermountain West 71 2016 Volume 3
Tracking Dinosaurs in BLM Canyon Country, Utah
Hunt-Foster, R.K., Lockley, M.G., Milner, A.R.C., Foster, J.R., Matthews, N.A., Breithaupt, B.H., and Smith, J.A.
Figure 2. Caption on following page.
Geology of the Intermountain West 72 2016 Volume 3
Tracking Dinosaurs in BLM Canyon Country, Utah
Hunt-Foster, R.K., Lockley, M.G., Milner, A.R.C., Foster, J.R., Matthews, N.A., Breithaupt, B.H., and Smith, J.A.
Figure 2 (figure on previous page). (A) Location of Copper Ridge Dinosaur Tracksite (after Foster, 2015). (B) Brontopodus
tracks. (C) Map of tracksite by Lockley and Hunt (1995). (D) Example of photogrammetric model of the Copper Ridge
Hispanosauropus trackway (Matthews, unpublished data). (E) Hispanosauropus (track 1, after Foster, 2015). (F) Participants
of the Mid-Mesozoic field conference learning photogrammetry techniques on the Hispanosauropus trackway at Copper
Ridge Dinosaur Tracksite from Neffra Matthews and Brent Breithaupt in 2014. (G) New interpretive signage installed at the
Copper Ridge Dinosaur Tracksite by the BLM in 2016. Art by Brian Engh (dontmesswithdinosaurs.com).
ens the case for the tracks having been made by one of tion. In fact, in addition to the main tracksite area (fig-
these genera. Megalosauripus appears to dominate large ure 3), which reveals at least 175 well-defined tracks and
theropod track samples from the base of the Morrison undertracks comprising more than 20 trackways, there
Formation (Tidwell Member); Hispanosauropus, and are two nearby areas, one to the north, with ~35 tracks
similar tracks are most common in the Salt Wash in at least eight trackways (Lockley and others, 2014c),
Member and its equivalents, suggesting taxonomic and one to the east with ~30 tracks. Both these areas are
turnover in the large theropod faunas during the early within ~100 m of the main site and represent the same
part of Morrison Formation deposition. surface, which is intermittently exposed over a large
area between and around these sites.
Stop 2 – Mill Canyon Dinosaur Tracksite The MCDT was developed for public visitation and
interpretation in 2014, opening to the public fully in
The Mill Canyon Dinosaur Tracksite (MCDT) in April of 2016. Partly with such developments in mind
the Cedar Mountain Formation (Ruby Ranch Member) the MCDT site has been subject to special study using
is the largest and most diverse of the eight known Cedar innovative strategies. First the site was considerably en-
Mountain tracksites. Although well known for its Lower larged, from the size of the original natural exposure,
Cretaceous vertebrate fauna in eastern Utah, the Cedar using mechanical excavation techniques, which are not
Mountain has previously yielded relatively few dinosaur often used at tetrapod tracksites. This phase of work was
tracksites. Among these the Arches National Park site funded through Univerity of Colorado by the Korean
(Lockley and others, 2004) and another yielding a large National Research Institute of Cultural Heritage. Sec-
assemblage of bird tracks (Lockley and others, 2015) are ond, the site was subject to a thorough photogrammet-
important locations within a 24 km (15 mi) radius of ric survey, which provided images for publications (e.g.,
the MCDT. Lockley and others, 2014b, figure 4) and interpretative
Preliminary results from the MCDT site (Lockley signs. Third, a boardwalk up to 80 m long and 2 m wide
and others, 2014b, 2014c) indicate the presence of at was installed over the site so that visitors can “walk with
least eight diagnostic ichnotaxa including three distinct the dinosaurs” without stepping on or damaging the
theropod track morphotypes identified as Irenesauri- tracks (figure 3). A shade structure was also installed.
pus, a Dromaeosauripus-like form, and an un-named Utah Friends of Paleontology (UFOP), Moab Giants,
ichnite. Poorly preserved bird tracks have also been Canyonlands Natural History Association (CNHA),
identified. Sauropod tracks include Brontopodus and and Grand County Trail Mix were community partners
manus-only sauropod undertracks. Ornithopod tracks in these efforts during most phases of the project.
resemble Caririchnium. The MCDT has revealed a number of enigmatic
The tracks occur in the upper part of the Ruby traces that can broadly be described as slip and scratch
Ranch Member, which mostly consists of gray, calcar- marks. Some resemble swim tracks but cannot defini-
eous mudstone with micritic limestone beds and nod- tively be placed in this category. Likewise the largest of
ules. However, the track bed is complex lithologically, these traces, a pair of elongate grooves, are tentatively
and is best described as a light gray, microcrystalline inferred to be of possible crocodylian origin (Lockley
impure chert, with a hardness of 5.5. The hardness of and others, 2014b). An herbivore coprolite was also
the track-bearing layer has contributed to its preserva- found in the middle of the main site (Lockley and oth-
Geology of the Intermountain West 73 2016 Volume 3
Tracking Dinosaurs in BLM Canyon Country, Utah
Hunt-Foster, R.K., Lockley, M.G., Milner, A.R.C., Foster, J.R., Matthews, N.A., Breithaupt, B.H., and Smith, J.A.
Figure 3. Caption on following page.
Geology of the Intermountain West 74 2016 Volume 3Tracking Dinosaurs in BLM Canyon Country, Utah
Hunt-Foster, R.K., Lockley, M.G., Milner, A.R.C., Foster, J.R., Matthews, N.A., Breithaupt, B.H., and Smith, J.A.
Figure 3 (figure on previous page). (A) Map of the Mill Canyon Dinosaur Tracksite (MCDT) modified after Lockley and
others (2014c). (B) Carmelopodus-like track. (C) Irenesauripus. (D) Caririchnium-like track. (E) Hatcherichnus-like trace. The
MCDT also contains sauropod tracks that include Brontopodus and manus-only sauropod undertracks. (F to H). Signage at
the MCDT. (I) Completed trail, which opened on April 1, 2016. Scale = 10 cm (4 in). Photographs by BLM.
Figure 4. (A) Breithaupt and Matthews
conducting systematic stereoscopic imagery
acquisition of the main track-bearing surface at
the Mill Canyon Dinosaur Tracksite (MCDT),
Utah (Lower Cretaceous Cedar Mountain
Formation) in summer 2014. (B) A single
didactyl theropod track from MCDT (center
image); color depth map with relative depths
recorded in cm (left image); and Orthorectified
image (right image), 1 mm (0.04 in)
topographic contour map. (C) Orthorectified
image mosaics composed of over 1000 images.
Yellow inset box of area shown in 4D. (D) Inset
showing detail of a small portion of the surface
from 4C as a color depth map. (E) A single
theropod track from MCDT (center image);
color depth map with relative depths recorded
in cm (left image); Orthorectified image (right
image), 5 mm (0.2 in) topographic contour
map. See Lockley and others (2014b) and
Matthews and others (2016).
ers, 2014c). The site has considerable potential for fur-ever existed on Earth. Located on the western margin
ther excavation and future study. of Pangaea for almost 10 million years, this erg is esti-
mated to have covered an area of approximately 644,000
Stop 3 – Synapsid Burrows km2 (400,000 mi2), now represented by over 322,000
km2 (200,000 mi2) of exposed eolian sandstone outcrop.
The Lower Jurassic (Pliensbachian-Toarcian) Na- Vertebrate and invertebrate trace fossils have long been
vajo Sandstone of Utah, Colorado, New Mexico, and known from the Navajo, and its equivalents, and are
Arizona, along with the Nugget Sandstone to the north usually associated with relatively small carbonate lenses
(Idaho, Wyoming) and the Aztec Sandstone to the south representing interdunal lakes.
(Nevada, California), represents the largest erg to have At the Rocky Tops Burrow Site near Moab, Utah,
Geology of the Intermountain West 75 2016 Volume 3Tracking Dinosaurs in BLM Canyon Country, Utah
Hunt-Foster, R.K., Lockley, M.G., Milner, A.R.C., Foster, J.R., Matthews, N.A., Breithaupt, B.H., and Smith, J.A.
“enigmatic” cylindrical and mounded sandstone struc- that dig similar structures include prairie dogs, voles,
tures are present in eolian sandstone beds, at times and naked mole rats. A few specimens observed by
below carbonate beds. Two main types of burrows are Riese and others (2011) exhibit scalloped walls, likely
represented at this site: Type I and Type II (figure 5). Al- created by the organism’s hand during excavation mo-
ternative interpretations proposed for these structures tions (figure 5).
include rhizoliths, termite nests and other invertebrate Type II is represented by dorsoventrally flattened
traces, concretions, fluid escape features, and wind-ero- structures comprised of horizontal to subhorizontal,
sion features (Lucas and others, 2006; Riese and oth- helical, curving, and simple branching tunnels that may
ers, 2011). Type I burrow structures have been defined lead to an enlarged chamber (figure 5, Smith, 1987;
as being comprised of high-density, complex networks Groenewald and others, 2001; Miller and others, 2001;
of interconnected Y- and T-branching tunnels, with Hasiotis and others, 2004; Riese and others, 2011).
inclined ramps, horizontal to subhorizontal large-di- These are thought to have been created by therapsids,
ameter structures preserved as differentially weath- based on their simple architecture, burrow diameter,
ered low-relief mounds. The walls are predominantly and raised floors. They are typically less complex and
smooth, with evidence of rhizoliths and small-diame- less interconnected. Parallel longitudinal ridges on the
ter, passively filled burrows. These are most comparable surface of the burrows could possibly represent scratch-
with large complex burrow systems and mounds pro- es produced by the organism’s claws, beaks, or incisors.
duced by social and eusocial mammals that show in- These types of burrows likely represent a permanent
terconnected, sinuous, and multiple branching tunnels dwelling and brooding structure. Similar modern tun-
and ramps. Whereas no body fossils of mammals have nels include those of alligators, crocodiles, some mon-
been found within the Navajo Sandstone (although the- itor lizards (Varanus mertensi), and skinks, along with
rapsids have been found in this unit), modern animals modern mammals such as the platypus, armadillo, and
Figure 5. Type I and II burrows (from Riese and others, 2011). (A, C to E, and G) Y-branching structures—(C) with an out-
ward branching structure and (D) with an outward branching element. (F) T- and Y-branching structures. (I to L) Sinuous
architecture. (M and N) Surficial morphology of Type I structures with scallops marks by arrows. (N) Represents and extant
mole burrow cast with scallops. (H and O) Type II structures and surficial morphology; (H) is the raised floor creating a
bioturbated morphology and (O) shows three parallel ridges on the lobes, indicated by arrows. Scale bar = 1 cm.
Geology of the Intermountain West 76 2016 Volume 3Tracking Dinosaurs in BLM Canyon Country, Utah
Hunt-Foster, R.K., Lockley, M.G., Milner, A.R.C., Foster, J.R., Matthews, N.A., Breithaupt, B.H., and Smith, J.A.
aardwolf. The Type II burrows were likely excavated by toward the top of the Church Rock Member is called
large tritylodontid therapsids, based on size and com- Red Ledge (figure 6); again, mostly composed of con-
parisons to similar burrows from the Permian and Tri- glomerates deposited in a large braided river system.
assic of Antarctica and South Africa. A tritylodontid The Red Ledge beds are very fossiliferous. Finally, be-
therapsid was recently found in the Navajo Sandstone in tween the contact of the Church Rock Member and
Sand Flats Recreation Area east of Moab. An additional the Lukachukai Member of the Wingate Sandstone is
Navajo Sandstone tritylodontid from Arizona was as- a mostly fluvial unit called the Big Indian Rock beds
signed to Kayentatherium (Winkler and others, 1991) (Martz and others, 2014; figure 6). The Big Indian Rock
but was regarded as a mammalian cynodont of the Tri- beds contain the Last Phytosaur skull (see below) and
tylodontidae by Sues and others (1994). This specimen important tracksites located on Eagle Nest Ridge (see
was also found in interdunal deposits. discussion below) to the south.
DAY 2: LATE TRIASSIC–EARLY JURASSIC Lisbon Valley Research
OF SAN JUAN COUNTY Current investigation of Lisbon Valley began with
exhaustive and thorough fieldwork in 2004 through
Lisbon Valley Stratigraphy and Paleontology
2015 by Andrew R.C. Milner and the St. George Dino-
The overall history and most recent lithostratigraph- saur Discovery Site at Johnson Farm (SGDS). In 2009,
ic and vertebrate biostratigraphic assessment of Lisbon the Natural History Museum of Utah (UMNH) and
Valley were thoroughly covered by Martz and others other researchers from Colorado and Arizona joined
(2014). The Upper Triassic Chinle Formation within the team resulting in spectacular findings of plants, in-
Lisbon Valley is estimated to be late Norian-Rhaetian vertebrates, vertebrates, and invertebrate and vertebrate
in age (~208-201 Ma) based on body fossils, especially trace fossils (figure 7). Extensive study of vertebrate
aetosaurs and phytosaurs (Martz and others, 2014). body fossils from Lisbon Valley has been conducted on
The Chinle Formation is unconformably underlain fishes (Schaeffer, 1967; Milner and others, 2006a, 2006b;
by the Lower Permian Cutler Group and overlain by the Gibson, 2013a, 2013b, 2015), with some work on phyto-
Upper Triassic-Lower Jurassic Wingate Sandstone (fig- saurs, especially the Last Phytosaur (Morales and Ash,
ure 6). The Chinle in Lisbon Valley is divided into the 1993; Lucas and others, 1997; Martz and others, 2014),
Kane Springs beds capped by the Church Rock Member and aetosaurs (Martz and others, 2014). Several publi-
(also called the Dolores Formation in nearby Colorado cations are presently being written to describe many of
and the Rock Point Formation in Arizona and New Mex- the new vertebrate specimens both from Lisbon Valley
ico; Lucas (1993) refers to the Chinle as a group rather and Indian Creek (see discussion on Indian Creek), as
than formation). Salt tectonics in the region during the well as the vertebrate trace fossils and localities summa-
Triassic likely resulted in the complete erosion of the rized below (table 1).
lower part of the Chinle Formation, the entire Moenko-
pi Formation, and the upper part of the Cutler Group. Stop 4 – Lisbon Valley
Locally, the lower part of the Kane Springs beds incised
Camp Hill Swimtracks (figure 8)
paleovalleys into the Cutler Group (Martz and others,
2014). However, precise stratigraphic correlation of the A set of large didactyl to tetradactyl swimtracks re-
Chinle Formation in the Lisbon Valley outlier is prob- ferable to Characichnos isp. occur on a large fallen block
lematic; especially the Kane Springs beds (Martz and of sandstone preserved in concave epirelief (Milner and
others, 2014). Lockley, 2016; figure 8B). Swimtracks may represent
The uppermost Kane Springs beds contain a prom- punting marks left by a large phytosaur swimming or
inent conglomerate in the region called Black Ledge bottom-walking in a channel, although orientation of
(Martz and others, 2014; figure 6). Another distinct unit travel cannot be determined. The best preserved set of
Geology of the Intermountain West 77 2016 Volume 3Tracking Dinosaurs in BLM Canyon Country, Utah
Hunt-Foster, R.K., Lockley, M.G., Milner, A.R.C., Foster, J.R., Matthews, N.A., Breithaupt, B.H., and Smith, J.A.
Figure 6. Stratigraphy of the Chinle Formation in the Lisbon Valley area. (A) Generalized stratigraphy of Skull Ridge showing
the positions of Black Ledge and Red Ledge beds (modified from Ash and others, 2014). (B) Detailed stratigraphic section of
Skull Ridge (modified from Martz and others, 2014). Unit/subunit numbers: 1 – Cutler Group, 2 – lower Kane Springs beds,
3 – middle Kane Springs beds, 4 – upper Kane Springs beds, 5a–Black Ledge, 5b to f – lower Church Rock Member, 6–Red
Ledge, 7a to f – upper Church Rock Member, and 8–Wingate Sandstone. (C) Explanation for B (modified from Martz and
others, 2014).
Geology of the Intermountain West 78 2016 Volume 3Tracking Dinosaurs in BLM Canyon Country, Utah
Hunt-Foster, R.K., Lockley, M.G., Milner, A.R.C., Foster, J.R., Matthews, N.A., Breithaupt, B.H., and Smith, J.A.
Figure 7. Examples of vertebrate
body fossils from the Chinle
Formation of Lisbon Valley. (A)
Hemicalypterus weiri Schaeffer,
1967 (USNM V 23425),
composite part and counterpart
image courtesy Sarah Z. Gibson
(modified from Gibson, 2015). (B)
Synorichthys stewarti Schaeffer,
1967 (UMNH VP 22906). (C)
Lophionotus sanjuanenesis Gibson,
2013a (UMNH VP 19420A).
(D) Tanaocrossus kalliokoskii
Schaeffer, 1967 (UMNH VP
22905). (E) Lophionotus chinleana
Gibson, 2013b (UMNH VP
19417 = holotype). (F) Partial
articulated phytosaur skeleton with
osteoderms, dorsal vertebrae, ribs,
and pelvis (UMNH VP 24650).
(G) Crocodylomorpha new genus
and species partial skull (UMNH
VP 21212). (H) “Redondasaurus”
(Machaeroprosopus) sp. skull
(UMNH VP 24304). (I) Typothorax
coccinarum incomplete lateral
osteoderm (UMNH VP 24232).
Scales A-E and I = 1 cm (0.4 in); G
= 2 cm (0.8 in); and F, H = 10 cm
(4 in).
swimtracks was replicated (SGDS 1196) and measures Additional in situ examples of smaller Characichnos
30 cm long by 17 cm wide (12 in long by 7 in wide), and traces occur to the southwest on Camp Hill with a swim
the deepest point being 1.7 cm (0.67 in) in the middle direction toward the northwest. Other isolated swim
of the center digit. Sets of circular depressions arranged tracks occur on Eagle Nest Ridge to the north and Three
in arches may represent a trace called “Pentasauropus” Step Hills to the south.
(figure 8C; Lockley and Hunt, 1995), although identi-
fication as actual trace fossils cannot be determined at Robert’s Canyon Tracksite (figure 9)
this site.
The fallen block containing these tracks match- This is a very informative tracksite set in a sequence
es well with the Red Ledge beds of the Church Rock of fluvial channel beds containing abundant invertebrate
Member above (Martz and others, 2014; figure 8A). The trace fossils throughout. This site is immediately below
thicker sandstone layer is cross-bedded representing a the Wingate Sandstone in the uppermost Church Rock
broad, braided river system (Martz and others, 2014). Member of the Chinle Formation situated just above
Geology of the Intermountain West 79 2016 Volume 3Tracking Dinosaurs in BLM Canyon Country, Utah
Hunt-Foster, R.K., Lockley, M.G., Milner, A.R.C., Foster, J.R., Matthews, N.A., Breithaupt, B.H., and Smith, J.A.
Table 1. Species and ichnospecies lists for the Chinle Forma- deep mud cracks, and they resemble sites preserved
tion in the Lisbon Valley area. to the north on the northeastern slope of Redd Ridge.
Vertebrate Species Only one of these additional localities preserves a single
Actinopterygii indet. Evazoum gatewayensis track.
Hemicalypterus weiri Schaeffer, 1967 (Fig. 7A) The Robert’s Canyon Tracksite preserves abundant
Lophionotus sanjuanenesis Gibson, 2013a (Fig. 7C) Brachychirotherium (figure 9A to 9D and 9G), although
Lophonotus chinleana Gibson, 2013b (Fig. 7E)
Synorichthys stewarti Schaeffer, 1967 (Fig. 7B)
possible Evazoum (figure 9E and 9F) and Rhynchosau-
Cionichthys dunklei Schaeffer, 1967 roides tracks are also present. All tracks at this site are
Lasalichthys hillsi Schaeffer, 1967 preserved in concave epirelief. Latex peels were created
Tanaocrossus kalliokoskii Schaeffer, 1967 (Fig. 7D) under permit for the longest Brachychirotherium track-
Tanaocrossus sp. way and for two small possible Evazoum tracks in a sin-
Arganodus dorotheae (Case, 1921)
gle trackway. Abundant smaller tracks were recognized
Chinlea sorenseni Schaeffer, 1967
over the entire surface after the latex peels were later
Phytosauria indet. (Fig. 7F) examined at the SGDS. Because of the steep-walled can-
Pseudopalatine indet.
yon, low-angle light on the tracksite surface makes these
“Redondasaurus” (Machaeroprosopus) sp. (Fig. 7H)
Machaeroprosopus sp. smaller tracks invisible. All of the tracks on this surface
are small, compared to other sites in Lisbon Valley.
Aetosauria indet.
Typothorax sp.
Typothorax coccinarum Cope, 1875 (Fig. 7I)
Eagle Nest Tracksites (figure 10)
Paracrocodylomorpha indet. The Big Indian Rock beds (Martz and others, 2014)
Crocodylomorpha indet. at the contact between the Church Rock Member of the
Crocodylomorpha n. gen. et sp. (Fig. 7G) Chinle Formation and the Lukachukai Member of the
Wingate Sandstone contain abundant tracks locally with
Vertebrate Ichnofossils
most preserved as natural casts (figures 10A and 10B).
Undichna isp.
Rhynchosauroides isp. Brachychirotherium (figure 10C) and small Grallator
Gwyneddichnium isp. (figure 10D and 10E) are locally abundant, preserved in
Brachychirotherium parvum (Hitchcock, 1889) medium- to coarse-grained sandstone. Tracks occur on
Brachychirotherium sp. at least four stratigraphic levels and most surfaces have
Evazoum gatewayensis Lockley and Lucas, 2013
not been mapped because the ledges are long and nar-
Evazoum isp.
“Pseudotetrasauropus” isp. row with in-situ tracks on the undersides. One surface
“Pentasauropus”? has poorly preserved Grallator in concave epirelief and
Apatopus isp. can be oriented into its in-situ position (figure 10B and
Grallator isp. 10F). Grallator tracks range in size from 15.5 cm (6.1 in)
Grallator?
long and 9 cm (4 in) wide to 6 cm (2 in) long and 4.5 cm
Characichnos isp.
(1.8 in) wide with several tracks displaying phalangeal
pads. These Grallator tracks are small in comparison to
the Red Ledge beds (Martz and others, 2014). Tracks older and larger Grallator found at a site near the base
occur on a high northern ridge in the step-walled “Rob- of the Red Ledge beds on Schaeffer Ridge to the south
ert’s Canyon” named after its co-discoverers, Robert (figure 10G). Brachychirotherium cf. parvum are mostly
Baldazzi and Robert Gay. David Slauf, however, found incomplete and have an average length/width of 12 cm
this tracksite along with several other small tracksites (5 in) by 14 cm (6 in), respectively.
located farther to the south and southeast of the Rob- Several small, in situ tracksites have also been re-
ert’s Canyon locality. Most of these nearby tracksites corded within the lower part of the Lukachukai Mem-
only have Brachychirotherium preserved along with ber of the Wingate Sandstone on the southeastern side
Geology of the Intermountain West 80 2016 Volume 3Tracking Dinosaurs in BLM Canyon Country, Utah
Hunt-Foster, R.K., Lockley, M.G., Milner, A.R.C., Foster, J.R., Matthews, N.A., Breithaupt, B.H., and Smith, J.A.
Figure 8. Camp Hill outcrop and tracks. (A) Locality of fallen phytosaur swim track block (red arrow) showing where it
originated from in the Red Ledge beds (yellow arrow), Church Rock Member, Chinle Formation. Photo courtesy of Jeff
Martz (University of Houston). (B) Best set of large phytosaur swim tracks (i.e., Characichnos isp. = SGDS 1196 replica). Scale
= 10 cm. (C) cf. “Pentasauropus” on same surface with swim tracks.
of Eagle Nest Ridge. All of the tracks on these surfaces ented into their correct positions so that trackway direc-
are natural cast of theropod footprints, many attributed tions in relationship to current flow can be determined.
to Grallator (figure 10H and 10I). These tracks along with a nearby block containing swim
tracks (figure 11F) come from the uppermost portion of
Redd Ridge North and South (figure 11) the Red Ledge beds of the Church Rock Member.
At least two stratigraphic levels of tracks on the north
side of Redd Ridge in the upper Church Rock Member Stop 5 – Last Phytosaur (figure 12)
preserve footprints in concave epirelief and convex hy- The Last Phytosaur represents the dorsal impression
porelief respectively. Small and large mudcracks are of a pseudopalatine phytosaur skull probably referable
present on both surfaces. Unfortunately, dense foliage to “Redondasaurus” (figure 12A and 12B). The name
on very steep, covered slopes, makes their exact strati- Last Phytosaur was coined by Morales and Ash (1993)
graphic position uncertain. The natural cast surface re- because of the skulls stratigraphic position, either in
sembles desiccated horizons to the south near Robert’s the basal Wingate Sandstone, or within the uppermost
Canyon, north of Steen Canyon, and farther to the west Church Rock Member of the Chinle Formation (see
in the Indian Creek area. Only Brachychirotherium are also Lucas and others, 1997). Martz and others (2014)
preserved at all of these localities (figure 11A to 11C). named the unit (8a in figure 12C) the Big Indian Rock
On the southeast side of Redd Ridge, two large fall- beds, placing it within the lowermost Wingate.
en blocks covered in current ripple marks have two long Morales and Ash (1993) mention a second skull
and parallel Evazoum gatewayensis trackways (figure found nearby and this may be represented by MNA
11D and 11E) and a shorter Brachychirotherium track- V10650 which was recently prepared at the SGDS. In
way. By looking at the block shapes, both can then be ori- recent years the SGDS and UMNH crews have collected
Geology of the Intermountain West 81 2016 Volume 3Tracking Dinosaurs in BLM Canyon Country, Utah
Hunt-Foster, R.K., Lockley, M.G., Milner, A.R.C., Foster, J.R., Matthews, N.A., Breithaupt, B.H., and Smith, J.A.
Figure 9. Robert’s Canyon Tracksite in the upper Church Rock Member, Chinle Formation. (A) Tracksite map. (B)
Brachychirotherium trackway 1 drawing showing track set 4-6 only. (C) Brachychirotherium trackway 2 showing entire
exposed trackway, inverted photo of latex peel. (D) Drawing of Brachychirotherium trackway 2. (E) Drawing of two tracks in
possible Evazoum isp. trackway. (F) Photo of tracks in E. (G) First track in Brachychirotherium trackway 2 showing metatarsal
impression. Scale in B, D, E = 50 cm (20 in); C = 10 cm (4 in); scale in G = 5 cm (2 in). A and B, D and E are interpretive
drawings made by Martin G. Lockley during 2011 field season.
an additional three “Redondasaurus” skulls from Skull lower part of Red Ledge on the south side of Skull Ridge
Ridge within less than a 0.4 km (0.25 mi) of the Last to the east of the Last Phytosaur skull. This tracksite
Phytosaur skull. However, all of these specimens come includes abundant invertebrate burrows and grazing
from the Red Ledge beds lower down in the Church trails, with the only identifiable specimens of Apato-
Rock Member (Martz and others, 2014). pus—possibly representing phytosaur tracks (figure
Finally, vertebrate tracks have been found in the 12D and 12E), and poorly-preserved Brachychirotheri-
Geology of the Intermountain West 82 2016 Volume 3Tracking Dinosaurs in BLM Canyon Country, Utah
Hunt-Foster, R.K., Lockley, M.G., Milner, A.R.C., Foster, J.R., Matthews, N.A., Breithaupt, B.H., and Smith, J.A.
Figure 10. Eagle Nest Ridge Tracksites. (A) Southeast side of Eagle Nest Ridge showing the position of the track-bearing Big
Indian Rock beds and Lukachukai Member of the Wingate Sandstone. (B) Track-bearing Big Indian Rock beds on Eagle Nest
Ridge. The two upper fallen slabs are those mapped in F. (C) In situ natural cast tracks on underside of ledge in Big Indian
Rock beds. Brachychirotherium (white arrow left center) and Grallator (yellow arrow top right). (D) Isolated Grallator natural
cast from Big Indian Rock beds (UMNH VP 24637). Scale = 2 cm (0.8 in). (E) Grallator natural cast (UMNH VP 21876).
Scale = 2 cm (0.8 in). (F) Two mapped Grallator-dominated slabs in B. Scale = 10 cm (4 in). (G) Two natural cast Grallator
tracks from the base of Red Ledge beds of Church Rock Member from Schaeffer Ridge. These are the largest Grallator from
the Chinle Formation of the region (UMNH VP 22885). Scale = 5 cm. (H) Natural cast tracks preserved in Lukachukai
Member on Eagle Nest Ridge (photo courtesy David Slauf, volunteer at SGDS). (I) Same track surface as in H showing at least
20 theropod tracks on two stratigraphic levels (photo courtesy David Slauf).
um (figure 12F). The Red Ledge beds represent a thick
underlain by the Wingate Sandstone, and the Chinle
braided river sequence (Martz and others, 2014). Formation. In the uppermost part of the Church Rock
Member of the Chinle, approximately 15 m below the
Stop 6 – Shay Canyon Tracksite (figure 13) Chinle-Wingate contact lies the Shay Canyon Tracksite
Upon entering the Indian Creek Valley from the (Lockley and Hunt, 1995, p. 77–78, figure 3.8; called
south, we drive down through the Kayenta Formation, Rock Point Formation by Hunt and Lucas, 2007, p. 223).
Geology of the Intermountain West 83 2016 Volume 3Tracking Dinosaurs in BLM Canyon Country, Utah
Hunt-Foster, R.K., Lockley, M.G., Milner, A.R.C., Foster, J.R., Matthews, N.A., Breithaupt, B.H., and Smith, J.A.
Figure 11. Tracks from Redd Ridge. (A) Brachychirotherium parvum trackway with mudcracks preserved as actual tracks
(UMNH VP 22334). Scale = 10 cm (4 in). (B) Close-up of second set manus and pes tracks in A. Scale = 5 cm (2 in). (C)
Partial Brachychirotherium trackway with unusual gate. First pes tracks has elongate metatarsal impression (UMNH VP
21875). Scale = 10 cm (4 in). (D) Two large current ripple-covered Evazoum track blocks fallen from Red Ledge beds in
background with Wingate Sandstone behind that. (E) Latex peel showing examples of two Evazoum gatwayensis tracks in
trackway from lower block shown in D. (F) Possible swim track set from Red Ledge beds. Scale = 5 cm (2 in).
Although only briefly described by Lockley and atic tracks include several enigmatic scratch and scrape
Hunt (1995), very little has been published on this very marks, which were first interpreted as phytosaur swim
large tracksite, which is by far the largest Chinle track- tracks, although this is highly speculative (Lockley and
site exposed in the region. The site preserves over 250 Hunt, 1995). Hunt and Lucas (2007) identify tracks at
tracks on a single bedding surface (figure 13A), dom- the Shay Canyon site as Brachychirotherium thuringi-
inated by Brachychirotherium tracks and trackways acum, Anchisauripus sillimani, and Pentasauropus sp.
(figure 13B). Less common Atreipus-like tracks are Several patches of fish debris (figure 13C) have been
also reported, along with possible Pentasauropus tracks interpreted as coprolites by Lockley and Hunt (1995).
(Lockley and Hunt, 1995; figure 3.10). Other problem- It is possible that these are simply disarticulated and/or
Geology of the Intermountain West 84 2016 Volume 3Tracking Dinosaurs in BLM Canyon Country, Utah
Hunt-Foster, R.K., Lockley, M.G., Milner, A.R.C., Foster, J.R., Matthews, N.A., Breithaupt, B.H., and Smith, J.A.
Figure 12. “Last Phytosaur” and tracks found nearby on Skull Ridge. (A) In situ pseudopalatine phytosaur skull impression at
Last Phytosaur locality. Note white bone to the right in photos and abundance of large associated mudstone clasts. Jeff Martz
pictured for scale. (B) Close-up of Last Phytosaur skull. Green clay still remains in replica from first replication of specimen
housed at Museum of Northern Arizona (MNA). Yellowish material is old latex left behind from a failed replica attempt. This
has since been removed for UMNH and SGDS latex peel. Finger on right is pointing to end of snout. Scale = 10 cm (4 in). (C)
Stratigraphic section through Last Phytosaur site (black arrow) situated in Big Indian Rock beds (unit 8a) in basal Wingate
Sandstone (modified from Martz and others, 2014). (D) Apatopus natural cast tracks (UMNH VP 24921). Scale = 2 cm (0.8
in). (E) Apatopus natural cast tracks (UMNH VP 24919). Scale = 2 cm (0.8 in). (F) Pair of Brachychirotherium natural cast
tracks with abundant invertebrate burrows (UMNH VP 24920). Scale = 5 cm (2 in).
associated fish remains since fossil fishes are very abun- tosaurs, aetosaurs, crocodylomorphs, theropods, me-
dant locally within the Church Rock Member in both toposaurs, and a variety of fishes have been collected
the Indian Creek and Lisbon Valley areas. in the Indian Creek valley from 2013-2016 by UMNH
At Indian Creek, the Chinle Formation unconform- and SGDS field crews. Several small tracksites have also
ably overlies the Lower Triassic Moenkopi Formation been recognized in the upper part of the Owl Rock (see
which is very thin here compared to other areas. The Track City below) and Church Rock Members of the
lower member of the Chinle superficially resembles Chinle, and the Lukachukai Member of the Wingate.
the Kane Springs beds as seen in Lisbon Valley, but is
identified as the Owl Rock Member (Martz and others, Stop 7 – Track City (figure 15)
2014). The upper member is the Church Rock Member
capped by the Wingate Sandstone (figure 14). The “Track City” Tracksite is the oldest tracksite in
Fossils are locally abundant within the Chinle For- the Chinle Formation known from the Indian Creek
mation and Wingate Sandstone in Indian Creek. Phy- area. It is located in the upper part of the Owl Rock
Geology of the Intermountain West 85 2016 Volume 3Tracking Dinosaurs in BLM Canyon Country, Utah
Hunt-Foster, R.K., Lockley, M.G., Milner, A.R.C., Foster, J.R., Matthews, N.A., Breithaupt, B.H., and Smith, J.A.
Figure 13. Shay Canyon Tracksite. (A) Northern 30 m of tracksite map; each bar = 1 m (3 ft); A = Atreipus-like trackways,
B = Brachychirotherium trackways, C = coprolites. (B) Southern 26 m (85 ft) of tracksite map; each bar = 1 m (3 ft). (C)
Rose diagram of northern map track orientations. (D) Rose diagram of southern map track orientations. (E) Stratigraphic
section of the uppermost Chinle Formation at Shay Canyon Tracksite showing track horizon (footprint). Scale = 5 m (16
ft). (F) Part of southern tracksite surface and the upper part of the Chinle Formation capped by the Wingate Sandstone. (G)
Close-up of trampled track surface. (H) Sketch of right Brachychirotherium manus and pes set. Scale = 10 cm (4 in). (I) Right
Brachychirotherium manus and pes set on tracksite surface. (J) Sketch of right Atreipus-like track. Scale = 10 cm (4 in). (K)
Left Atreipus-like track on tracksite surface. (L) In-situ fish debris in possible coprolite. Scale = 2 cm (0.8 in). A-E, H, J are all
modified from Lockley and Hunt (1995, figure 3.8).
Member and holds Brachychirotherium (UMNH VP 15H). This locality still requires excavation.
26000 in figure 15A and 15F; UMNH VP 25993, figure As mentioned above, several other tracksites have
15D to 15E), Rhynchosauroides (figure 15A and 15G), been identified within the upper part of the Church
Evazoum gatewayensis (UMNH VP 26000, figure 15A Rock Member within the Indian Creek region. Many
to 15C), Gwyneddichnium (UMNH VP 25992, figure of these are small, isolated sites similar to those in the
15I), and several unidentified tracks (figure 15A and Lisbon Valley area, only preserving a few tracks. The
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